High energy density magnetic springs using spatially modulated magnetic fields technology

BACKGROUND

Magnetic springs offer benefits of compactness and high energy density, similar to fluidic springs, but without the disadvantages of leakage and temperature dependence. In addition, magnetic springs offer the possibility of constant force over the operating range, as opposed to mechanical springs, which feature a force that varies linearly according to displacement.

SUMMARY

The present invention provides a magnetic spring based on spatially modulated magnetic field patterns and having a customized force curve over the operating range. Additional embodiments of the invention provide a magnetic spring with multiple force curves, such that the active force curve is selected according to the azimuthal angular position of the spring's sliding shaft relative to the stator.

Therefore, according to embodiments of the present invention, there is provided a magnetic spring comprising: (a) a stator having a first spatially modulated magnetic field pattern of magnetic regions; and (b) a slider having a second spatially modulated magnetic field pattern of magnetic regions; wherein the stator and the slider are mechanically constrained to have a spatial relationship such that: (i) the slider and stator are mechanically free to undergo an axial movement relative to one another along a predefined axis over a predefined axial range, resulting in an axial displacement of the slider and stator relative to one another; (ii) the first spatially modulated magnetic field pattern and the second spatially modulated magnetic field pattern interact magnetically to have a magnetic interaction according to the spatial relationship and the axial displacement, so that an axial force arising from the magnetic interaction exists between the stator and the slider; and (iii) the axial force between the stator and the slider is a function of the axial displacement of the slider and the stator relative to one another along the predefined axis within the predefined axial range.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, both as to organization and method of operation, together with objects, features, and advantages thereof, may best be understood by reference to the following detailed description when read with the accompanying drawings in which:

<figref idref="DRAWINGS">FIG. 1</figref> is an exploded isometric view illustrating the components of a magnetic spring according to an embodiment of the present invention.

<figref idref="DRAWINGS">FIG. 2</figref> shows axial views separately illustrating the stator and slider of the magnetic spring of <figref idref="DRAWINGS">FIG. 1</figref>.

<figref idref="DRAWINGS">FIG. 3</figref> illustrates a non-limiting example of a spatially modulated magnetic field pattern of regional magnetic orientation in a magnetic spring stator according to the present invention.

<figref idref="DRAWINGS">FIG. 4</figref> shows axial views separately illustrating the stator and slider of a magnetic spring according to another embodiment of the present invention.

<figref idref="DRAWINGS">FIG. 5</figref> illustrates a non-limiting example of a force curve for a magnetic spring according to an embodiment of the present invention.

<figref idref="DRAWINGS">FIG. 6A</figref> is an axial view illustrating a magnetic spring according to another embodiment of the present invention with a slider in a first azimuthal orientation.

<figref idref="DRAWINGS">FIG. 6B</figref> is an axial view illustrating the magnetic spring of <figref idref="DRAWINGS">FIG. 6A</figref>, with the slider in a second azimuthal orientation.

<figref idref="DRAWINGS">FIG. 7</figref> illustrates a non-limiting example of two respective force curves for the magnetic spring of <figref idref="DRAWINGS">FIG. 6A</figref> and <figref idref="DRAWINGS">FIG. 6B</figref> in the two azimuthal orientations.

It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.

DETAILED DESCRIPTION

In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, and components have not been described in detail so as not to obscure the present invention.

<figref idref="DRAWINGS">FIG. 1</figref> illustrates the components and makeup of a magnetic spring <b>100</b> according to an embodiment of the present invention. A stator <b>101</b> has a protective outer casing <b>103</b> and a thin low-friction inner bearing <b>105</b> around a recess <b>109</b> inside which a slider <b>111</b> fits and slides in and out in directions <b>115</b> along a longitudinal axis <b>117</b>. Between casing <b>103</b> and bearing <b>105</b> is a magnetic material having a spatially modulated magnetic field pattern of magnetic regions, such as in representative regions <b>107</b>A, <b>107</b>B, <b>107</b>C, <b>107</b>D, and <b>107</b>E. Spatially modulated magnetic field patterns of magnets and magnetic regions are known in the art, and techniques of creating predetermined spatially modulated magnetic field patterns of magnetic regions are also known in the art. According to embodiments of the present invention, such techniques may be utilized to create spatially modulated magnetic field patterns of magnetic regions in the components of a magnetic spring as described herein.

In certain embodiments of the invention, stator <b>101</b> and slider <b>111</b> feature patterns which are spatially-modulated both axially and azimuthally.

Slider <b>111</b> contains a magnetic material, also having a spatially modulated magnetic field pattern of magnetic regions, such as in representative regions <b>113</b>A, <b>113</b>B, <b>113</b>C, <b>113</b>D, and <b>113</b>E. <figref idref="DRAWINGS">FIG. 2</figref> shows enlarged axial views of stator <b>101</b> and slider <b>111</b>. The magnetic interaction between the spatially modulated magnetic field pattern of magnetic regions in stator <b>101</b> and the spatially modulated magnetic field pattern of magnetic regions in slider <b>111</b> give rise to an axial force between stator <b>101</b> and slider <b>111</b>, which is a function of the axial displacement of slider <b>111</b> relative to stator <b>101</b>.

<figref idref="DRAWINGS">FIG. 3</figref> shows a non-limiting example of a spatially modulated magnetic field pattern of magnetic regions in representative regions <b>107</b>A, <b>107</b>B, <b>107</b>C, <b>107</b>D, and <b>107</b>E, according to an embodiment of the present invention. The arrows in the representative regions shown in <figref idref="DRAWINGS">FIG. 3</figref> represent the respective magnetic moment vectors of the regions, with the arrows pointing according to the common convention, from the respective south poles to the respective north poles. The term “spatially modulated magnetic field pattern” denotes that the specific pattern of magnetic orientations in the magnetic regions is according to a predetermined arrangement.

In some embodiments of the present invention, slider <b>111</b> may be mechanically free to be rotated inside stator <b>101</b> in directions <b>119</b> (<figref idref="DRAWINGS">FIG. 1</figref>) to change azimuthal orientation. In other embodiments, slider <b>111</b> may be constrained to a particular range or set of values of azimuthal orientation. In specific embodiments, constraints may be imposed magnetically, by the particular spatially modulated magnetic field patterns of the magnetic regions; in other specific embodiments, constraints may be imposed mechanically, such as by a keyed channel, or by the geometry of the stator and slider. For example, instead of using a cylindrically-symmetrical geometry for the slider and its recess, as in <figref idref="DRAWINGS">FIG. 1</figref> and <figref idref="DRAWINGS">FIG. 2</figref>, a prismatic geometry lacking continuous rotational symmetry can be used. <figref idref="DRAWINGS">FIG. 4</figref> shows axial views of a non-limiting example of a prismatic stator <b>401</b> with a square cross-section and having an outer casing <b>403</b> and an inner bearing <b>405</b> for a corresponding slider <b>411</b>. In this example, stator <b>401</b> contains a spatially modulated magnetic field pattern of magnetic regions, such as in representative regions <b>407</b>A, <b>407</b>B, and <b>407</b>C; and slider <b>411</b> also contains a spatially modulated magnetic field pattern of magnetic regions, such as in representative regions <b>413</b>A, <b>413</b>B, and <b>413</b>C. In still other embodiments of the present invention, the geometry of the slider and the stator recess can be such that there is no rotational symmetry at all, in which case the slider-stator azimuthal angular alignment is fixed so long as the slider remains inserted in the stator. If the slider is removable from the stator, however, the azimuthal angular alignment can be changed by removal, reorientation, and re-insertion.

<figref idref="DRAWINGS">FIG. 5</figref> illustrates a non-limiting example of a force curve <b>505</b> for a magnetic spring according to an embodiment of the present invention. Stator <b>101</b> and slider <b>111</b> are mechanically free to undergo an axial movement relative to one another along axis <b>117</b> (<figref idref="DRAWINGS">FIG. 1</figref>) over a predefined range in a direction <b>507</b> or in a direction <b>509</b>. Slider <b>111</b> and stator <b>101</b> have a spatial relationship with a magnetic interaction between the spatially modulated magnetic field pattern of magnetic regions in slider <b>111</b> with the spatially modulated magnetic field pattern of magnetic regions in stator <b>101</b>. The magnetic interaction results in axial force curve <b>505</b>, which is a function of the axial displacement of slider <b>111</b> relative to stator <b>101</b>. Axial force <b>505</b> is plotted according to a force axis <b>501</b> against an axial displacement axis <b>503</b>. The precise form of force curve <b>505</b> depends on the specific properties of the spatially modulated magnetic field patterns of magnetic regions. In this non-limiting example, a portion <b>515</b> exhibits a relatively constant force over a portion of the displacement range, and another portion <b>517</b> exhibits a different relatively constant force over another portion of the displacement range. Embodiments of the present invention provide different force curves by having different spatially modulated magnetic field patterns of magnetic regions in the slider and/or stator.

<figref idref="DRAWINGS">FIG. 6A</figref> is an axial view illustrating a magnetic spring according to another embodiment of the present invention that provides different force curves in the same magnetic spring, which are selected by rotating the slider to different predetermined angular positions relative to the angular position of the stator. A stator <b>601</b> has an index mark <b>609</b> in one angular position, and another index mark <b>617</b> in another angular position. A slider <b>611</b> has an indicator <b>615</b> showing an azimuthal angular alignment with index mark <b>609</b>, so that representative magnetic regions <b>613</b>A, <b>613</b>B, and <b>613</b>C of slider <b>611</b> align with representative magnetic regions <b>607</b>A, <b>607</b>B, and <b>607</b>C, respectively, of stator <b>601</b>. <figref idref="DRAWINGS">FIG. 6B</figref> is an axial view illustrating the magnetic spring of <figref idref="DRAWINGS">FIG. 6A</figref>, but with slider <b>611</b> rotated azimuthally so that indicator <b>615</b> shows an azimuthal angular alignment with index mark <b>617</b>, whereupon representative magnetic regions <b>613</b>A, <b>613</b>B, and <b>613</b>C of slider <b>611</b> do not align with representative magnetic regions <b>607</b>A, <b>607</b>B, and <b>607</b>C, respectively, of stator <b>601</b>. Instead, a different set of magnetic regions <b>623</b>A, <b>623</b>B and <b>623</b>C on slider <b>611</b> align with the set of magnetic regions <b>607</b>A, <b>607</b>B and <b>607</b>C respectively. <figref idref="DRAWINGS">FIG. 7</figref> illustrates non-limiting examples of a force curve <b>711</b> corresponding to the slider-stator azimuthal angular displacement of <figref idref="DRAWINGS">FIG. 6A</figref>, and a force curve <b>713</b> corresponding to the slider-stator azimuthal angular displacement of <figref idref="DRAWINGS">FIG. 6B</figref>. Both curve <b>711</b> and curve <b>713</b> are plotted according to a force axis <b>701</b> against an axial displacement axis <b>703</b> for displacement in a direction <b>619</b>.

A single magnetic spring according to this embodiment of the present invention can provide different spring characteristics for a particular application simply by rotating the slider to a different position relative to the stator. Since the rotation is relative to the slider, this embodiment can be used in a configuration where the slider has a fixed rotational position, and it is the stator which is rotated instead, to select the spring characteristics.

While certain features of the invention have been illustrated and described herein, many modifications, substitutions, changes, and equivalents will now occur to those of ordinary skill in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.